The present invention relates to a data recording and reproducing apparatus for use with a record address video tape recorder (VTR) of the like and, more particularly, to a record address data insertion device for such an apparatus which allows one to record, or insert, address data and other desired data in a recording medium such as a video tape while maintaining the VTR in a playback mode operation. The words "address data" used herein should be understood to imply those data which are adapted to search for a desired portion of data which are carried in the recording medium.
As regards a VTR, while it is often desired to record various address data such as a date in a video tape in which video material has been previously recorded (referred to simply as a recorded tape hereinafter), switching the VTR from a reproducing mode operation to a playback mode operation is troublesome. In light of this, there has ben proposed a system which enables one to activate a recording system of a VTR while maintaining the VTR in a playback mode so as to activate a record or write head, thereby writing various types of data during several Hs (horizontal scans) of one field.
In a system of the kind described, video signals reproduced by a VTR from a recorded tape are applied to a sync separation circuit so that horizontal and vertical sync signals provided by the sync separation circuit are used as sync signals for the insertion of the data. The problem with this prior art system is that noise is generated at the beginning and end of a data insertion period due to activation of switches which are connected to a record amplifier and others of the VTR and, in addition, synchronization is disturbed over approximately ten Hs that occur before and after the insertion period due to malfuntions of the automatic gain control (AGC) circuit of a playback amplifier. The result is the distortions appearing in a television (TV) screen which prevents data from being accurately inserted into a recorded tape.